1. Field of the Invention
This invention relates to electrodes used in detecting low amplitude bioelectric signals.
2. Description of the Prior Art
The detection of low level signals in the midst of competing noise signals is not easily accomplished, particularly with low level signals acquired at the surface of the body. Competing noise signals can obscure low amplitude signals which, if not obscured, could provide important information about a patient's condition. The detection and analysis of signals degraded by noise is a common problem that has been addressed in many ways.
Where the frequency components of the desired signal and the noise signals are distinctly separated, significant noise reduction can be accomplished with proper frequency filtering without altering the underlying desired signal. Where there is significant overlap between the frequency spectrum of the noise signal and the desired signal, separation of the desired signal from the noise signal is more difficult. This is a common problem in the analysis of biophysical signals. One common technique to enhance repetitive or cyclical signals is signal averaging of the time-domain signals. This results in one enhanced cycle of the desired signal. This problem has motivated development of other more sophisticated techniques, some of which seek to provide enhanced signal representation cycle-to-cycle or in very short-term averages.
These more sophisticated techniques often require at least two pairs of electrodes to acquire at least two signals for comparison. There are two constraints on the acquired signals. First, the underlying desired signals must be very similar. Second, the noise in the acquired signals must be very dissimilar, that is uncorrelated.
It has been found that when standard electrodes are utilized, the morphology of the acquired bioelectric signals, such as those found in the initial and terminal portions of the QRS complex of an electrocardiogram (ECG), can be significantly and undesirably different in each signal, particularly when acquisition amplifiers used in the acquisition of the signals have a very high gain. Thus, a need remains in the art for electrodes suitable for the acquisition of bioelectric signals with similar morphologies.
It is an object of the present invention to provide an improved electrode for the measurement of low level bioelectric signals on the surface of the body amidst competing noise signals, such that the signals acquired with the electrodes of the present invention will generate waveforms having similar morphology.
It is still another object of the present invention to provide an improved electrode for the measurement of ECGs on the surface of the body, wherein the signals acquired with the electrodes of the present invention will have a similar morphology in the initial and terminal portions of the QRS complex.
It is another object of the present invention to provide an improved electrode for the measurement of low level signals amidst competing noise signals.
It is still another object of the present invention to provide an improved concentric electrode which is quickly and easily attached to and removed from the surface of the body.
It is a further object of the present invention to provide an electrode which is inexpensive to construct and which is quickly and easily affixed to a given surface and is non-shorting.